Photographic printing process



Dec '14, 1943.

W. MHCHAELIS PHOTGGRAPHIG PRINTING PROCESS Filed July 15, 1939 mu m INVENTOR Walter MiChae/is f? ATTOR EY Patented Dec. 14. 1943 u l'TEojsTA'rEs PATENT OFFICE rnorocaarnrc ranv'rmo raocass Walter Michaelis, Brussels-Forest, Belgium, as-

signor, by mesne assignments, to Chromogen, Incorporated, a. corporation or Nevada Application July 15, 1939, Serial No. 284,771

In Germany July 18,1938

The present invention relates to .a process for the manufacture of photographic prints.

The expression printing prototype. hereinafter used is intended to connote any image from which a print is taken in a photogaphlc printing process in which the same is disposedbetween the source of printing light and the printing layer whether said image be a black and white, monochrome or multi-color image and whether the same is an original or not. I

E a dye-image is printed onto a light-sensitive printing layer by the known photographic printing processes, it is essential that the printing light be absorbed by the dye of the-image to be printed, and that the same printing light influence a printing layer sensitive forthis light. For ex ampl, a magenta dye-image transparent to blue light and red light can be printed onto' a-greensensitive printing layerby means of green light which is absorbed by th magenta dye, but apparently it cannot be printed by the known process onto .a layer which is non-sensitive to green light but sensitive to blue or red light.

For certain purposes oi color photography, of which an exampleis given-in the following, it would be a great-simplification if an image could be printed with green light onto a layer non-sensitive to green, or more'broadly, ii the-printing with colored printi light pre-determined by the kind of printing p otetype used could be carried out on layers sensitive not for the, same light but for differently colored light rays. It is one object of the present invention to render this possible. I

To give an example of the caseswhere the above-described possibility would result in an important simplification oi the process, the case should be considered wherein a print or an'enlargement on paper is to be prepared from a three-color transparency, which may have been manufactured by any process.

cording to Bela Gaspars U. S. Patent No. 1,985,344,

dated December 25, 1934, is especially useful. --In such a material, for instance, the top layer is yellow front layer of the printing material;

,dyed yellow and is green-sensitive, the following layer is dyed magenta and is red-sensitive, the

iii

prints of color-correct originals.

14 Claims. (01. 959-2) blue light, because it is transparent to all other light. The yellow-dyed printing layer on the other hand is non-sensitive to blue light. The part-image dyed magenta in the original cannot be satisfactorily printed when illuminated with light other than green light, but the magentadyed printing layer into which this part-image has to be copied is non-sensitive to green light,

and it is the yellow layer into which this partimage must not be printed that issensitive to green light. In the same manner, the blue: green part-image of the printing prototype needs red light for printing, and in the printing material it is not the blue-green but the magenta layer that is sensitive to redllght. Therefore, it appears that it is not possible to. use the described material' to obtain directly color-correct Hitherto: therefore, the prints in this material have been prepared with the aid of individual part printing prototypes or with theaid of multi-colonprinting prototypes whose colors'difier from the natural colors, or according to Bela Gaspars U. S. Patent No. 1,998,891 dated January 22, 1935, screen images are converted into suitable printing prototypes by changing the screen. A simple process for printing directly from a color-correct original into the three-layer material above referred to has appeared to be impossible till now, because every single part-image of the prototype requires a special light, whereasin the printing material the layer into which the part-image in question For the manufac ;ture of color prints on paper, a three-layer material with .three pre-dyed layers sensitized acrear layer isdyed blue-green and is sensitive to w infra-red. Ifa print of a color-correct original is to be printed into such a materiahthe yellow partimageof the original must.'be printed intom ut the yellow part-image of the original cannot "be printed when illuminated'with light other than 65 must be printedis non-sensitive to thi light and requires a difierent light.

In the following I have described ajnew method whereby prints can be obtained even if the printing layer requires a diflerent light from that required for the printing prototype. According to the invention, this object will be achieved by plac- 'ing between the printing prototype and the print- 1 ing. layer a light-responsive device which, under the influence of the colored light transmitted by the transparent areas of the prototype and more or less absorbed by the opaque areas of the prototype, causes the light-sensitive printing layer to be influenced accordingly by light of a. diflerent spectral composition.

the luminescence and, if necessary, all other rays .of the luminescent light except those required for influencing the printing layer.

A photo-electric device responding to variations 01' colored light and controlling the luminosity of another light source emitting light of a different spectral composition is another example of a suitablelight-responsive device that may be used to bring about the change in the wave-length of the colored light, and this enables me to expose the printing layer to a light oi! a color different to that used to illuminate the printing prototype.

In order to explain the principle of thev invention in an individua1 case, the printing of a color-correct diapositive-screen-image or subtractive three-color image-onto a light-sensitive three-layer material such as that mentioned above as an example, will now be described.

For this purpose there is arranged between the original. and the printing layer a foil containing a substance, such as amino-fiuoranthrene, which fluoresces green on exposure to blue light, and the whole is then exposed to blue light of a narrow spectral range. In this case the fluorescent rays appear at those places where.the original is transparent to blue light and not at the places where the passage of blue light is prevented by the red and the green filter elements in the screen-image onby the yellow part-image in the subtractive three-color picture. All rays except the green fluorescent rays are obstructed by a green filter inserted between the fluorescent blue-green color.

subtractive three-color printing prototype is obtained.

The three latent silver images are thereupon developed and the printing material is then was a positive.

For the accompanying schematic drawing I have chosen an example which is especially illustrative of the effect of different sources of light acting upon fluorescent screens correspondingly responsive. This example relates to the printing of three differently colored part-images of a three-color original I into a printing material comprising three light-sensitive layers 2, 3 and 4 superimposed on a single support 5. The original l carries a series of three-color pictures, each color picture of the series being formed of three superposed dye-images of yellow, magenta and Three consecutive pictures of the series are shownin the drawing. Y reprev, sents the yellow-colored part-image of one of screen and the printing material, and in this manner a latent negative image of the blue screen part-image or of the yellow part-image of the subtractive three-color original is obtained in the yellow dyed green-sensitive printing layer. In the same manner a screen arranged between the original and the printing layer is used, which, on exposure to green light, fluoresces red. This screen may be produced by pouring a 7% aqueous-gelatin emulsion, to which has been added 0.3% of acid rhodamine, on to a transparent carrier in the proportion of about 700 cc. of colored gelatin solution per sq. metre. The original is now exposed to green light of a narrow spectral range, and all light rays except the red which there is no color index number, vide Sample No.17, Zaponechtfarbstoffe, I. G. 1330d by -I. G. Farbenindustrie A. G. This time the origg the original subtractive multi-color image is abthe multi-color pictures of the series, M represents the magenta-colored part-image of the same multi-color picture, and C represents the blue-green-colored part-image of the same multicolor picture, designated as Picure I in the following description. Similarly, Y", M'f and C" together constitute a second three-color picture of the series, designated hereinafter as Picture II. Y', M' and 0" represent the three partimages of a third multi-color picture of the series, designated in the following as Picture III.

In-the position shown in the drawing, multicolor Picture I is positioned between a light spurce 6 and the printing materiaLiwith the interposition of a blue light filter 1 between the light source 8 and Picture I. On the opposite side of Picture I there follows first a fluorescent screen 8 and then a green filter 9. Similarly, Picture II is in such a position that the light from light source [0 passes through a green filter ll, through multi-color Picture II onto a fluorescent screen !2; between the fluorescent screen l2 and the printing material there isra red filterl3. In the case of Picture III, I4 is a light source, I5 is a red filter, I6, is a fluorescent screen and I1 is a filter transmitting light of the long-wave red and the infra-red spectral regions.

In the printing material, layer 2 is sensitive to green light and dyed *yellow, layer 3 is sensitive to red and dyed magenta, and layer 4 .is sensitive to dark-red and infra-red and is colored blue-green.

'Of the fluorescent screens, 8 emits green light under the influence of blue light, 12 emits red light under the influence of green light, and I8 emits dark-red or infra-red light under the influence of yellow or red light.

In the position shown in the drawing, the blue light transmitted by filter I is absorbed by partimage Y, and at the places corresponding to sorbent for such light and if the magenta dye transmits the yellow light of the sodium lamp. All light rays except the dark-redv and infrared fluorescent rays of more than about 660 mu are excluded from the printing layer by a filter, such as Wratten fllter,No. 88a. A latent negative of the screen part-image that is red in the original, er or the blue-green part-imageof the the transparent areas of part-image Y there will be a green fluorescence in screen 8. The green fiuorescence'light acts through green filter 9 onto the green-sensitive layer 2 of the printing material and produces therein a latent print of Y. Similarly, the green light of light source In transmitted by'the transparent areas of partimage M"'causes red fluorescence in screen [2, which acts through filter l3 onto the red-sensitive layer 3 of the printing material, and produces therein a latent print oi-M".

The system of light sources,- filters and screens remaining in place, if now the original film and the printing film are both moved in the direction of the arrow into the next printing position, in which Picture I and als that area of the printing material already o print of Y are opposite light source I0, then green light from light source l and filter II will print M' into layer a in register with the latent print of Y; u from light source I4 and red filter l5 will print G." into layer 4 in register with the latent print of M". v

By moving the films a aim in the direction of the arrow into the nex printing position, in which Picture I and also. that area of the printing material which already contains the latent prints of Y and M are opposite light source and ll, then red light from light source It filter IE will print C into layer 4- in register with the existing latent prints of Y and M.

The printing material is now, developed and fixed, and then subjected to local dye destruction at the places where silver is present. The three superposed images Y, M and C together then form a positive three-color picture. The same applies to the other multi-color prints that are completed by further printing steps per- I formed in the same manner.

In the same manner the'red light from ll 'causesdarkred or infra-red fluorescence at the places of At the same time, red lightontaining the latent highly absorbed by the least transparent'parts of the colored record to be printed and which is transmitted by the other differently colored records of said subtractive multicolor picture, said fluorescent screen being responsive to said colored light andemitting a fluorescent light of difierent spectral composition, the fluorescent light being recorded in one of the light-sensitive silver halide emulsion layers of a multilayer material comprising a plurality of differently sening selectively a part image of a subtractive multicolor picture in which colored light,'chiefiy transmitted by the most transparent parts of the screen being responsive to said colored light and emitting light of a difierent spectral composition, the colored light emitted by the fluorescent screen being recorded on a light-sensitive photographic silver halide emulsion layer which issensitive to the fluorescent light.

4. A photographic printing process for printing selectively a part image of a subtractive multicolor picture in which colored light, chiefly trans- 1. A photographic printing process for printing the single color separation records-of a multi-' color picture formed by a plurality of differently colored separation records, wherein in rinting the single color separations a fluorescent screen is illuminated through said multicolor picture with colored light which is highly transmitted by the most transparent parts of the colored record to be printed and highly absorbed by the least transparent parts of the colored record to be printed,- said fluorescent screen being reoi' differently colored separation records, wherein inpriiiting%he single color separations a fluorescent screen is illuminated through said multicolor subtractive picture withcolored light which mitted by, the most transparent parts of the colored part image to be printed and by the other part images but highly absorbed by the least transparentportionsiof the part image to be printed, is used to iiluminate a light responsive light source through said multicolor picture, said light responsive light source being responsive to said colored light and emitting light of a different spectral composition, the light emitted by the light responsive light source being recorded on a light-sensitive silver halide emulsion layer substantially insensitive to light used to illuminate .said light responsive light source. Q

5. The process of selectively printing a colored part image of a subtractive multicolor picture comprising difierently coloredpart-images, on a I prises projecting said part image with'light pass ing through said multicolor picture and substantially absorbed by the coloring substance forming said part image but substantially unabsorbed by said other part images or at those portions of said part image where none of said coloring substance is present, upon a liuninescent screen responsive to said light -and emitting light of a said difierent spectral composition to whiiliih printing layer is sensitive, and exposi g said printing layer tov the luminescent image on said screen.

6. The process of selectively printing a colored part image of a subtractive multicolor picture comprising difierently coloredlpart-images, on a light sensitive silver halide emulsion printinglayer which is not sensitive to colored light rays absorbed to a substantial extentby the coloring substance forming said part image but which is sensitive to light not absorbed .to any substantial extent by said coloring substance, which com 3" parts of the colored record to'be printed and prises projecting said part image with light passing through said multicolor picture and substantially absorbed by the coloring substance forming said part image but substantially unabsorbed at those portions of said multicolor picture where none of said coloring substance is present, upon a fluorescent screen responsive to said light and emitting light of a difierent spectral composition to which said printing layer is sensitive, and exposing said printing layer to the fluorescent.

image on said screen.

'7. The process of selectively printing a colored part image of a subtractive multicolor picture comprising difierently colored part images, on one of the light sensitive silver halide layers of a multilayer material comprising a plurality of difierently sensitized silver halide emulsion layers, said one of said layers being insensitive to colored light rays absorbed to a substantial extent by the coloring substance forming said part image but sensitive to light not absorbed to any substantial extent by said coloring substance and another of said layers being sensitive to colored light rays absorbed to a substantial extent by the coloring substance forming said part image, which comprises projecting said part imagewith light substantially absorbed by the coloring substance forming said part image and substantially unabsorbed at those portions of said part image where none of said coloring substance is present, upon a fluorescent screen responsive to said light and emitting light of a different spectral composition to which said first mentioned silver halide layer of said multilayer material is sensitive, and exposing said first mentioned layer to the fluorescent image on said screen while screening said second mentioned layer from the light used in projecting said colored part image on said fluorescent screen.

8. In a system for producing a print of a single colored color separation record of a multi-color picture formed by a plurality of differently colored color separation records, a light sensitive silver halide printing layer diffusely dyed with a dyestuff having a color substantially the same as the coloringsubstance forming said colored record, said printing layer being sensitive to a range of light rays transmitted by said dyestufi and substantially insensitive to light rays absorbed by said dyestuff, means for illuminating said colored record with light substantially absorbed by the coloring substance forming said colored record and substantially unabsorbed at those portions of said colored record where no coloring substance is present, and means including a screen responsive to the unabsorbed light for reproducing an image of said colored record in difierently colored light transmitted by said dyestuff and to which said printing layer is sensitive, said printing layer being so positioned and arranged as to .be exposed to said last mentioned image.

9. A process for producing a photographic print from a single colored color separation record of a multi-color picture formed by a plurality of differently colored color separation records onto a light-sensitive silver halide emulsion printing layer which is sensitized to light other than the light with which said single record must be illuminated in the printing operation, which comprises illuminating a fluorescent screen through said multi-color picture with light substantially transmitted by the most transparent portions and substantially absorbed by the least transparent portions of said single record, said fluorescent screen being responsive to said light and emitting light of a different spectral composition including light to which the printing layer is sensitive, and exposing the printing layer to only that part of the light emitted by said fluorescent screen to which said printing layer is sensitive.

10. A process for producing a photographic print from a single colored color separation record of a multi-color picture formed by a plurality of differently colored color separation records onto a light-sensitive silver halide emulsion printing layer which is substantially insensitive to light for which the color of said single record is absorptive and which is sensitive to light freely transmitted by the color of said single record, which comprises illuminating a light responsive light source through said multicolor picture with light substantially transmitted by the most transparent portions and substantially absorbed by the least transparent portions of said single record, said light responsive light source being responsive to said light and emitting light of a different spectral composition including light to which the printing layer is sensitive, and exposing the printing layer to only that part of the light emitted by said light responsive light source to which said printing layer is sensitive.

11. A photographic printing process for printing the singe color separation records of a multicolor picture formed by a plurality of difierently colored separation records, wherein in printing the single color separations a luminescent screen is illuminated through said multicolor picture with colored light which is highly transmitted by the most-transparent parts of the colored record to be printed and highly absorbed by the least transparent parts of the colored record to be printed, said luminescent screen being responsive to said colored light and emitting aluminescent light of different spectral composition, the luminescent light being recorded in one of the light sensitive silver halide emulsion layers of a multilayer material comprising a plurality of difierently sensitized silver halide emulsion layers each sensitized to light emitted by the luminescent screen 'used in printing the record into said layer.

12. A photographic printing process for printing the single color separation records of a subtractive multicolor picture formed by a plurality of differently colored separation records, wherein in printing the single color separations a luminescent screen is illuminated through said multicolor subtractive picture With colored light which is highly transmitted by the most transparent parts of the colored record to be printed and highly absorbed by the least transparent parts of the colored record to be printed and which is transmitted by the other difierently colored records of said subtractive multicolor picture, said luminescent screen being responsive to said colored light and emitting a luminescent light of a different spectral composition,- the luminescent light being recorded in one of the lightsensitive silver halide emulsion layers of a multilayer material comprising a plurality of differently sensitized silver halide emulsion layers each sensitized to light emitted by the luminescent screen usedin printing the record into said layer.

13. A photographic printin process for printing selectively a part image of a subtractive multicolor picture in which colored light, chiefly transmitted by the most transparent parts of the colored part image to be printed and by the other part images but highly absorbed by the least other than the light with which saidsingle record transparent portions of the part image to be printed, is used to illuminate a luminescent/screen through said multicolor picture, said luminescent screen being responsive to said colored light and emitting light of a difierent spectral composition, the coloredlight emitted by the luminescent screen being recorded on a light-sensitive photographic silver halide emulsion layer which is sensitive to the luminescent light.

14. A process for producing a photographic print from a single colored color separation record of a multicolor picture formed by a plurality of differently colored color separation records onto a light-sensitive silver halide emulsion printing layer which, is sensitized to light must be illuminated in the printing operation, which comprises illuminating a luminescent screen through said multicolor picture with light substantially transmitted by the most trans-,

parent portions and substantially absorbed by the least transparentportions of said single record, said luminescent screen being responsive to said light and emittin light of a different spectral composition including light to which the printing .layer is sensitive, and exposing the printing layer to only that part of the light emitted by said luminescent screen to which said printing layer is sensitive.

WALTER MICHAELIS. 

